This series of projects is designed to increase our understanding or oral-nasal communication during speech production. These studies will (1) provide information about normal velopharyngeal function during production of a wide range of nonnasal utterance types, (2) examine the effects of systematic increases in oral- nasal coupling on perception or oral consonant productions, (3) determine the predictive nature of oral-nasal orifice area calculations obtained in the human vocal tract during speech, and (4) examine preoperative and longitudinal postoperative anatomic, physiologic, and perceptual measurements in association with surgery to establish velopharyngeal competence for speech. These studies represent, in part, a continuation of our previous aerodynamic investigations utilizing the equipment configuration and principles developed by Warren and his colleagues. However, these studies extend our work into new areas of research to include: (1) Determination of normal velopharyngeal function during oral speech sound production; this will lead to the development of a protocol for aerodynamic assessment of palatopharyngeal function; (2) Examination of the association between successive degrees of oral-nasal communication and oral speech sound production; this will determine the minimal degree of oral-nasal coupling that can be tolerated during production of perceptually normal oral utterances; (3) Assessment of the accuracy of oral-nasal orifice area estimates made in the human vocal tract using established pressure-flow methods; this will allow greater accuracy in future speech production studies; and (4) Examination of the relationship among preoperative and longitudinal postoperative perceptual, anatomic, and physiologic variables associated with pharyngeal flap surgery; this will identify variables associated with surgical success and also provide new information concerning factors associated with nasal obstruction. The Center for Craniofacial Anomalies provides a notable and diverse patient population having oral-nasal defects. This allows for significant expansion of our studies with the overall goal of defining parameters basic to our understanding of oral-nasal coupling during normal and abnormal speech production. Ultimately, this will lead to restoration of normal oral-nasal communication.